Well, you are gonna need a semi-mechanical bone for this unless you can find a RELIABLE mechanic.
The proper method for determining a battery drain is :
1. disconnect the negative battery cable.
2. connect a milliamp meter from the negative battery terminal to the connector on the negative cable.
3. the normal reading should be around 30 milliamps or so.
4. if it measures much higher, start pulling fuses in the box under the hood on the drivers side one at a time while watching the meter.
5. when you see the meter drop, you have located the AREA of the problem.

Get back with the fuse number in question and we'll go from there.

Hope this helps.
BTW: you can pick up a el-cheapo multimeter at Radio Shack if you don't already have one.